Swivel arm adjustment

ABSTRACT

A swivel arm adjustment device is provided for pivoting the armrest of a chair in order to allow multi-position adjustment to relieve stresses normally exerted on hands and wrists from improper hand positioning when typing. The swivel arm adjustment device includes a top member and a base member. The top member has a unitized construction and includes a centralized aperture, a first arcuate slot with resistance grooves and a second arcuate slot. The base member also has a unitized construction and includes a bushing with a snap-lock ring and a detent pin. The base and top members are adapted to be snapped together to form a pivotal coupling. The swivel arm adjustment device pivotally connects the armrest to the arm of a chair to provide a pivotal arrangement.

BACKGROUND OF THE INVENTION

[0001] This invention may be described as an improved armrest swivel adjustment which is attached to the arms of an office chair and provides for multi-position rotational adjustment and is designed to be assembled without the need for additional fastening hardware, significantly reducing the time and cost required for manufacture and assembly.

DESCRIPTION OF RELATED ART

[0002] Office chairs are equipped with an array of adjustments designed to allow an occupant to manipulate the chair into a position that allows them to work comfortably. With more computers in the workplace, employees are spending increased amounts of time seated in front of computer terminals which can lead to back pain and other ailments. Modern office chairs are ergonomically designed to allow the user of the chair to make adjustments to relieve stress and fatigue. Also, improper hand position when typing causes undue stress on wrists which can lead to carpel tunnel syndrome. To alleviate the stress on hands and wrists, chair armrests are adjustable to allow optimum positioning of the hands and wrists in relation to the keyboard. Adjustments may include height adjustment, lumbar support adjustment, back angle and height adjustment, lateral arm adjustment, vertical arm adjustment, forward and reverse armrest adjustment and swivel armrest adjustment. By allowing the armrests to pivot, the hands can be properly positioned in relation to the keyboard. Typical swivel armrest adjustments are comprised of many intricate pieces that take time to connect together during the assembly of the chair and usually require the use of tools. The additional time, hardware and manpower required to assemble the armrest swivel increases the overall cost of the product. Prior art devices that incorporate bolts to fasten the rotating armrest assembly together eventually loosen causing the armrest to improperly function. The prior art devices do not provide for a multiple position armrest assembly wherein the assembly is comprised of two pieces and can be snapped together without the use of tools.

SUMMARY OF THE INVENTION

[0003] This invention may be described as an office chair arm swivel adjustment device that allows an armrest to be pivoted to a number of predetermined positions. The swivel armrest adjustment device is comprised of two sections, a base member and an attached top member. The base member includes a snap-lock bushing with an integral snap ring that connects with a central aperture on the top member. The snap-lock bushing design allows the top member and the base member to be snapped together eliminating the need for screws and other fasteners. Since the two members can be snapped together, assembly during manufacturing can be automated, reducing production costs. The base member further includes a detent pin that, upon assembly, is positioned in an arcuate slot located on the top member. The arcuate slot contains resistance grooves to provide multiple adjustment positions. When the detent pin is moved from one position to the next, the arcuate slot is deformed in shape by protruding into an adjacent secondary arcuate slot, also located on the top member, allowing the arcuate slot to expand far enough to allow for the passage of the detent pin into the next resistance groove. The swivel adjustment device allows a user to incrementally pivot the chair armrest clockwise or counterclockwise up to 30 degrees to allow for the proper positioning of the users arms and hands in relation to the work station and the chair seat.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004]FIG. 1 is an exploded view of the swivel arm adjustment device of the present invention.

[0005]FIG. 2 is a perspective view of the upper surface of the top member of the swivel arm adjustment device.

[0006]FIG. 3 is a perspective view of the lower surface of the top member of the swivel arm adjustment device.

[0007]FIG. 4 is a perspective view of the upper surface of the base member of the swivel arm adjustment device.

[0008]FIG. 5 is a perspective view of the base member of the swivel arm adjustment device.

DETAILED DESCRIPTION OF THE INVENTION

[0009] While the present invention will be described fully hereinafter with reference to the accompanying drawings, in which a particular embodiment is shown, it is understood at the outset that persons skilled in the art may modify the invention herein described while still achieving the desired result of this invention. Accordingly, the description which follows is to be understood as a broad informative disclosure directed to persons skilled in the appropriate arts and not as limitations of the present invention.

[0010] A preferred embodiment of a swivel arm adjustment 10 of the present invention is shown in FIG. 1 attached to a chair 12. The swivel arm adjustment 10 is adapted to be fastened to a sleeve 14 which covers an arm 15 of the chair 12 such as an office or other style of chair, and to an armrest 16. The swivel arm adjustment device 10 allows the user to pivot the armrest 16 in various positions to increase comfort and reduce fatigue.

[0011] The swivel arm adjustment 10 is rectangular in shape and includes a top member 18 and a base member 20. The top member 18, as shown in FIGS. 2 and 3, includes a centralized aperture 22 a first arcuate slot 24 and a second arcuate slot 28. The top member 18 is a generally planar with a top surface 30, best shown in FIG. 2, and a spaced apart bottom surface 32, best shown in FIG. 3. The top surface 30 has a recessed center portion 34 and two raised end portions 36 and 37. The top surface 30 also includes two apertures 39 and 41 to allow access to the hardware on the base member 20. The two raised end portions 36 and 37 come in contact with and support the armrest 16 upon assembly. The recessed center portion 34 houses the centralized aperture 22 and the first and second arcuate slots 24 and 28. The recessed center portion 34 is reinforced by a rib 38 that extends from the centralized aperture 22 to end portions 36. The raised end portions 36 and 37, shown in FIG. 1, are planar and include apertures 40 and 42 to allow for the passage of fasteners 44 used to fasten the armrest 16 to the swivel arm adjustment 10.

[0012] The centralized aperture 22, as shown in FIG. 2, is ringlike in shape and extends upwardly from the recessed center portion 34. The top edge 46 of the aperture 22 is at an elevation slightly higher than the raised end portions 36 and 37. Outer circumference 48 is in contact with inside surface 50 of side walls 52 of the recessed center portion 34. The outer circumference 48 is also in contact with outside surface 54 of the first arcuate slot 24, opposite the resistance grooves 26. Inner surface 56 of the centralized aperture has a flat surface that acts as a bushing housing when the swivel arm adjustment system 10 is assembled. The inner surface 56 further includes an annular ridge 58 located near the bottom edge 60 which acts as a retaining ring to prevent detachment once the base member 20 is installed.

[0013] The wall surrounding the first arcuate slot 24, shown best in FIG. 2, is elevated above the recessed center portion 34 and includes a first side 64 and a second side 66. An inside surface 62 of the first side 64 is smooth to allow a detent pin 68 formed on the base member 20 to slide along the surface without resistance. The second side 66 of the inside surface 62 contains five resistance grooves 26 placed along the entire length of the side 66. The number of resistance grooves 26 can be varied depending on the number of adjustment positions desired. The resistance grooves 26 are arranged so that one of the grooves 26 has its centerline positioned midway along the length of the first arcuate slot 24. The four remaining resistance grooves 26 are paired on both sides of the center groove 26 creating a center detent position, two right detent positions and two left detent positions. The outer two resistance grooves 26 define edges 72 of the slot 24 preventing any further movement. The detent pin 68 is sized so that when it is inserted into the first arcuate slot 24 the outer circumference 70 is in contact with the inside surface 62 of the first side 64 and one of the resistance grooves 26, resisting any movement. Adjacent to the first arcuate slot 24 is a second arcuate slot 28 which is created by an absence of material on the bottom surface 32. The second arcuate slot 28 follows the curve of the outside surface 54 and wraps around the edges 72. The purpose of the second slot 28 is to provide space to allow for the encroachment of the second side 66 of the first arcuate slot 24. The outside surface 54 of the second side 66 is uninhibited by any structure allowing the second side 66 to bow outward when enough force is exerted by the detent pin 68, allowing the pin 68 to proceed to the next resistence groove 26. The pin 68 is moved by applying enough rotational force to the top member 18 causing it to move.

[0014] The bottom surface 32, as shown in FIG. 3, is generally planar with the exception of two depressions 74 located at the extremities of the surface 32. The bottom surfaces 76 of the depressions 74 house the apertures 40 and 42, visible from the top surface 30. The depressions 74, shown best in FIG. 3, are designed to receive the head of a screw or other fastener 44, shown in FIG. 1 as a bolt, to be recessed below the surface 32. The ability to recess the fasteners 44 is important to allow the center section 82 of the bottom surface 32 to pivot in relation to the base member 20. The center section 82, shown in FIG. 3, also includes the centralized aperture 22, the first arcuate slot 24 with resistance grooves 26 and the second arcuate slot 28. The centralized aperture 22, the first arcuate slot 24 with resistance grooves 26 and the second arcuate slot 28 are flush with a center section 82 of the bottom surface 32. The top member 18 is designed so that the entire structure can be made out of a single piece of material. While it is preferable to form the entire top member 18 out of injected molded plastic, it is also possible to construct the member 18 out of metals, resins or other materials. To aid in the pivot action of the top member 18, a plastic containing a self-lubricating additive such as graphite may be used.

[0015] The base member 20, of the swivel arm adjustment 10, as shown in FIGS. 4 and 5, includes a top surface 84 and a spaced apart bottom surface 86. The base member further includes four edges 87, 88, 89, 90. The top surface 84 is generally planar and includes a central bushing 92 and detent pin 68 which extend from the surface 84. The top surface 84 further includes two apertures 94 and 95 and two notches 96. The central bushing 92 is circular in shape and has an inner surface 98 and an outer surface 100. The outer surface 100 includes an integrated annular snap-ring 102 located near the top edge 104 of the central bushing 92. The snap-ring 102 incorporates a beveled upper edge 106 designed to allow the bushing 92 to be pressed into the aperture 22 on the top member 18, snapping them together. The lower edge 108 forms a ledge, preventing disassembly by interlocking with the top surface 59 of the annular ridge 58. When the bushing 92 is pressed into the centralized aperture 22 the pressure exerted by the snap-ring 102 against the annular ridge 58 causes the walls 91 of the bushing 92 to constrict and the walls of the aperture 22 to expand, allowing the snap-ring 102 to pass by the annular ridge 58 and expand outwardly locking the two members together. The diameter of the snap-ring 102 is sized so that it is in contact with inner surface 56 of the aperture 22. While the fit between the aperture 22 and the bushing 92 involves surface contact, it is noted that the two elements are sized to allow pivotal rotation of the top member 18 with respect to the base member 20. The detent pin 68 is cylindrical in shape and affixed to the top surface 84 along the center line of the length of the base member 20. The detent pin 68 has been positioned so that when the base member 20 and the top member 18 are aligned and pressed together, the detent pin 68 slides into the center resistance groove 26 of the first arcuate slot 24. The apertures 94 and 95 are oriented in a staggered configuration, diagonal from the other. The apertures 94 and 95 further include a stepped bore 110, shown best in FIG. 4, to allow the head of a fastener 112, shown in FIG. 1, to be recessed below the top surface 84. Apertures 94 and 95 allow the use of fasteners 112 to attach the swivel arm adjustment 10 to the sleeve 14 of the chair 12. The top surface 84 of the base member 20 is in slidable contact with the bottom surface 32 of the top member 18 upon assembly. The notches 96 on the base member 20 are placed at opposing ends along edges 87 and 89. The notches 96 are designed to allow the fasteners 44 to be removed and installed from the armrest 16, shown in FIG. 1, when the chair 12 is either assembled or disassembled. The bottom surface 86, as shown in FIG. 5, includes a plurality of ribs 114 in order to add flexural strength to the base member 20. The base member 20 along with the central bushing 92 and detent pin 68, in the preferred embodiment, are formed in a unitized fashion out of a single piece of material. While it is preferred to form the base member 20 from plastic, other materials such as metal or resin can be used, as well as various methods of manufacture such as injection molding and casting. Also, lubricants can be added to the plastic or metal to aid in the pivotal movement of the swivel arm adjustment 10.

[0016] During the assembly of office chair 12, shown in FIG. 1, at the factory incorporating the swivel arm adjustment 10, the top member 18 is attached to the armrest 16 by inserting the top surface 30 into the inside hollow of the armrest 16 and fastening the top member 18 and the armrest 16 together with screws 44. Similarly, the bottom member 20 is placed upon the top of the sleeve 14 and fastened to the sleeve 14 with the use of screws 112. Once the members are properly fastened, the aperture 22 of the top member 18 and the bushing 92 of the base member 20 are aligned and a force is exerted to snap the two members together. Once attached, a pivotal connection is formed and cannot be easily disassembled. The swivel arm adjustment 10 allows the armrest 16 of a chair to pivot either clockwise or counterclockwise through a predetermined number of positions without the use of tools, reducing the time required for assembly.

[0017] Various features of the invention have been particularly shown and described in connection with the illustrated embodiment of the invention, however, it must be understood that these particular arrangements merely illustrate, and that the invention is to be given its fullest interpretation within the terms of the appended claims. 

What is claimed is:
 1. A swivel armrest adjustment for a chair comprising: a base member pivotally connected to a top; a detent pin extending from said base member; a bushing also extending from said base member; a locking ring formed on said bushing and adapted to secure said base member in locking pivotal engagement with said top member; an aperture formed on said top member and adapted to receive said bushing; an annular ridge formed on said aperture and adapted to secure said bushing; and an arcuate slot also formed in said top member and adapted to receive said detent pin, whereby pivotal rotation of the armrest is accomplished by pivotal movement of said top member around said bushing of said base member.
 2. A swivel armrest adjustment according to claim 1, wherein said bottom member, said detent pin, said bushing and said locking ring comprising a single, unitary piece formed of plastic.
 3. A swivel armrest adjustment according to claim 1, wherein said top member comprising a single, unitary piece formed of plastic.
 4. A swivel armrest adjustment according to claim 1, including one or more resistance grooves formed on an inner wall of said arcuate slot, each groove adapted to releasably engage said detent pin thereby providing one or more predetermined positions for securing said armrest with respect to said base member.
 5. A swivel armrest adjustment according to claim 4, wherein said top member includes a second arcuate slot that allows movement of said detent pin between said resistance grooves by allowing a wall of said arcuate slot to deform.
 6. The swivel armrest adjustment according to claim 1, wherein said top member includes a plurality of apertures to allow for connection to an armrest pad by means of fasteners.
 7. The swivel armrest adjustment according to claim 1, wherein said bottom member includes a plurality of apertures to allow for the attachment of fasteners for connection to a vertical arm of the chair.
 8. The swivel armrest of claim 1 in which said base member and said top member can be snapped together as a subassembly by inserting said bushing thru said aperture and said detent pin thru said arcuate, slot and forcing said locking ring past said annular ridge thereby securing said base member and said top member together while providing for pivotal rotation of one with respect to the other within predetermined limits.
 9. The swivel armrest adjustment according to claim 1, wherein said bottom member includes a plurality of notches sized to allow for the passage of fasteners.
 10. The swivel armrest adjustment according to claim 1, wherein said bottom member includes raised ribbing to increase resistance to flexing.
 11. A swivel armrest adjustment for a chair comprising: a top member; an aperture formed in said top member; a first and a second arcuate slot also formed in said top member; a base member; a bushing extending from said base member; a detent pin also extending from said base member; said aperture adapted to receive said bushing form a locking pivotal connection; whereby pivotal rotation of the armrest is accomplished by pivotal movement of said top member around said bushing of said base member. 